1. Field of the Invention
This invention generally relates to hot beverage brewers, such as hot coffee brewers and iced tea abstract brewers and hot tea brewers and, more particularly, to such brewers of the type that spray hot water upon ingredient contained within a brew basket to dissolve the ingredient to make the brewed beverage or brewed beverage abstract.
2. Discussion of the Prior Art
Coffee brewers and hot tea abstract brewers or hot tea brewers of the type that have a brew basket within which is contained the beverage ingredient such as ground coffee beans or tea leaves, through which hot water is passed are well know. Examples of such brewers are shown the following U.S. Pat. No. 5,000,082 issued Mar. 19, 1991 to Lassota for “Beverage Maker and Method of Making Beverage” and U.S. Pat. No. 6,148,717 issued Nov. 21, 2000 to Lassota for “Beverage Maker with Intermittent Beverage Liquid Dispenser and Apparatus and Method for Uniform Contact of Brew Ingredient with Brew”, and reference should be made to these patents and the patents cited therein for details of the construction and operation of such brewers.
Briefly, in most of such brewers the hot water is passed through a spray head in the form of a cup shaped container with a closed top for receipt of hot water from a hot water tank and a flat, circular bottom spray plate containing an array of spray holes. The spray plate in known brewers is made of stainless steel. The hot water passes through the array of spray holes to cumulatively create a hot water spray, or shower, that falls on the top surface of a ingredient contained within the brew basket and then seeps through and partially dissolves the ingredient to form the freshly brewed beverage.
Due to the presence of lime, in various mineral forms and other minerals and mineral compounds, such as iron, dissolved in the hot water and the evaporation of the hot water in contact with the top and bottom surfaces of the spray plate and the inlets, outlets and side surfaces of the spray holes, calcium oxide, calcium sulfate, magnesium sulfate, calcium silicate and magnesium silicate and other mineral deposits build up on these surfaces and over time can clog entirely or partially obstruct the spray holes. Such residue build up is referred to as “liming”.
Even if the spray holes are only partially obstructed, the time it takes for a given quantity of hot water to pass through the spray plate is increased as compared to when there is no obstruction. In some brewers, in which the total quantity of hot water is predetermined and simply drained or “dumped” through the spray head, the total quantity is not effected by the liming but the total length of time for dispensing the hot water is increased and thus the duration of the brew cycle is increased.
In other brewers, in which the selected quantity of hot water is measured by passing the water at a presumed uniform rate for a pre-selected dispense time period, the dispenser period will not necessarily be altered by spray hole partial or complete clogging from liming will not necessarily change the dispense time period but can result in a reduction of the total quantity of hot water dispensed and a consequential alteration in the strength of the brewed beverage.
In either event, the “throughput”, i.e. the total quantity of coffee that can be made over a given time period using successive brew cycles is reduced. In addition, the degree of control over the hot water dispense time period and the total quantity of hot water dispensed that is needed for production of brewed beverage of uniform and preselected characteristics is lost. Ultimately, if the spray plate is not cleaned of the liming residue, the entire array of spray holes can become so clogged that the brewer will not function.
This liming problem has been addressed by attempting to reduce the quantity of calcium and other minerals dissolved in the water before it is passed through the spray head by means of lime and mineral commutation systems or reduction systems. While such dissolved mineral reduction reduces the rate of liming accumulation, it also requires the extra costs of purchase, maintenance and chemical supply replenishment for operation of the mineral commutation system, and if not all the liming and mineral deposits problems are removed from the water, liming residue accumulation will be reduced but not eliminated.
In the absence of a lime and mineral reduction and depending upon the level of dissolved calcium and other mineral compounds in the hot water, the only other solution to the liming problem has been frequent, routine, sometimes even daily, mechanical brushing or other cleaning of the spray plate to remove the calcium deposits from within and around the spray holes. Such cleaning is labor intensive and disables the brewer from operation during the cleaning. In addition, removal of the spray plate generally requires the use of tools to disassembly the plate from the spray head body.
Another problem with know spray head assemblies is that the velocity of the water droplets onto the top surface of the ingredient in the brew basket is directly related to the water pressure from the hot water dispense system and may impact the surface of the ingredient with sufficiently high impact energy to disadvantageously mechanically disturb the layer of ingredient and create undesirable splatter.